Oregon - Significance region: Local
| Myrtle Arms Apartment Building |
| Nasburg-Lockhart House |
| Nauke, William and Nannie, House |
| Neighborhood House |
| Neighbors of Woodcraft Building |
| Nelson, Carl E., House |
| Nelson, Otto W. and Ida L., House |
| Nerdrum-Conrad House |
| Nerdrum, Hjalte, House |
| Nevada-California-Oregon Railway Passenger Station |
| New Cliff House |
| Newell, Edwin, House |
| New Fliedner Building |
| New Heathman Hotel |
| New Houston Hotel |
| New Imperial Hotel |
| New Logus Block |
| Newman United Methodist Church |
| New Redmond Hotel |
| New Taggart Hotel |
| Nicholas-Lang House |
| Nichols, Dr. A. S., House |
| Nichols, Dr. Herbert S., House |
| Nichols House |
| Nicolai-Cake-Olson House |
| Nininger, Amos and Vera, House |
| Noonan-Norblad House |
| North Bank Depot Buildings |
| North Palestine Baptist Church |
| Northwestern Electric Company-Alberta Substation |
| Northwestern National Bank Building |
| Northwest Fence and Wire Works |
| Oak Grove Schoolhouse |
| Oak Hills Historic District |
| Odd Fellows Building |
| Odem, Milton, House |
| O'Donnell, E. J., House |
| O'Kane Building |
| O.K. Jeffery Aircraft Factory |
| O.K. Theatre |
| Olallie Lake Guard Station |
| Olallie Meadows Guard Station |
| Old First National Bank Building |
| Old First National Bank of Prineville, and Foster and Hyde Store |
| Old Garfield School |
| Old Placer Mine |
| Olds, Wortman and King Department Store |
| Old Town Historic District |
| Old US Post Office |
| Old Woodburn City Hall |
| Oleson, Ole and Polly, Farmhouse |
| Olsen and Weygandt Building |
| Olson, August, House |
| Olson, Charles and Fae, House |
| Olsson, Captain Bror W., House |
| Olympic Apartment Building |
| Olympic Cereal Mill |
| Oregon-American Lumber Company Mill Office |
| Oregon Bank Building |
| Oregon City Carnegie Library |
| Oregon City Masonic Lodge |
| Oregon City Municipal Elevator |
| Oregon Cracker Company Building |
| Oregon Electric Railway Passenger Station |
| Oregon Mutual Merchant Fire Insurance Association Office |
| Oregon Portland Cement Building |
| Oregon Power Company's Springfield Substation |
| Oregon Short Line Railroad Depot |
| Oregon State Bank Building |
| Oregon Trunk Passenger and Freight Station |
| Oriental Apartments |
| Ormonde Apartment Building |
| Orth, John, House |
| Osborn Hotel |
| Osgood Ditch |
| Otis Elevator Company Building |
| Ott, David and Marianne, House |
| Owyhee Grocery |
| Pacific Building |
| Pacific Coast Biscuit Company Building |
| Pacific Cooperative Poultry Producers Egg-Taking Station |
| Pacific Hardware and Steel Company Warehouse |
| Pacific Spruce Saw Mill Tenant Houses |
| Packard Service Building |
| Page and Son Apartments |
| Page, Judge C. H., House |
| Painter's Woods Historic District |
| Palace Hotel |
| Palestine Lodge |
| Pallay Apartments |
| Pallay Building |
| Palmer, John, House |
| Parelius, Martin, Fourplex |
| Parker, J. J. and Hazel, House |
| Parker Meadows Shelter |
| Parker, Moses, House |
| Parker School |
| Parkview Apartments |
| Parrish, William Albert and Anna May Bristow, Farmstead |
| Parrott, Moses, House |
Data from United States Park Service and Wikidata
